Vincent A. Henneken

In many monitoring scenarios, repeated and operator-independent assessments are needed. Wearable ultrasound technology has the potential to continuously provide the vital information traditionally obtained from conventional ultrasound scanners, such as in fetal monitoring for high-risk pregnancies. This work is an engineering study motivated by that setting. A 144-element annular capacitive micromachined ultrasonic transducer (CMUT) is hereby proposed for 3-D ultrasound imaging. The array is characterized by its compact size and cost-effectiveness, with a geometry and low-voltage operation that make it a candidate for future wearable integration. To enhance the imaging performance, we propose the utilization of a Fermat’s spiral virtual source (VS) pattern for diverging wave transmission and conduct a performance comparison with other VS patterns and standard techniques, such as focused and plane waves. To facilitate this analysis, a simplified and versatile simulation framework, enhanced by GPU acceleration, has been developed. The validation of the simulation framework aligned closely with expected values (0.002 ≤ MAE ≤ 0.089). VSs following a Fermat’s spiral led to a balanced outcome across metrics, outperforming focused wave transmissions for this specific aperture. The proposed transducer presents imaging limitations that could be improved in future developments, but it establishes a foundational framework for the design and fabrication of cost-effective, compact 2-D transducers suitable for 3-D ultrasound imaging, with potential for future integration into wearable devices.

The growing interest in artificial skin-based tactile systems requires sufficiently accurate, stretchable, low-power mechanical sensors. In this study, we present a novel capacitive device and an evaluation method capable of retrieving the force vector and determining the position of the loading point on an extended area without the application of a large matrix of individual sensors. With this tool, we can simultaneously increase the extractable information from an extended surface area and reduce the complexity, thereby the power consumption of the system. Thus, an alternative path is opened toward robotic tactile sensing by using a small array of sensors but covering a relatively large receptive field. Even a single sensor can meet the requirements of specific devices—for example, in catheters—to detect tissue hardness, bending, or narrowing of the arteries or veins. Apart from the medical and robotic applications, the flexibility in processing the Flex2Rigid platform enables the mimicry of human fingers or hands with integrated sensors and driving circuits.